Terminal Device and Retransmission Method for Dynamic Tdd Ul/Dl Configuration

1. A terminal apparatus capable of reconfiguring a configuration pattern of subframes to one of a plurality of configuration patterns, each of the plurality of configuration patterns defining transmission timings of one or more downlink subframes used for downlink communication and one or more uplink subframes used for uplink communication within a frame, the terminal apparatus comprising: determining circuitry, which, in operation, determines at least one first retransmission process to be continued after reconfiguration of the configuration pattern from among retransmission processes that belong to an old configuration pattern before the reconfiguration, wherein the determination of the at least one first retransmission process is made based on an association relationship between uplink subframe numbers and respective retransmission process numbers within a base frame, the base frame being a frame that includes at least one uplink subframe defined at a same transmission timing as another uplink subframe defined by a new configuration pattern after the reconfiguration, wherein the base frame is assigned a frame number which is divisible by a least common multiple between a first frame cycle associated with the old configuration pattern and a second frame cycle associated with the new configuration pattern, and the association relationship between the uplink subframe numbers and the respective retransmission process numbers within the base frame is uniquely determined by a combination of the old configuration pattern before the reconfiguration and the new configuration pattern after the reconfiguration; and determines at least one second retransmission process to which the at least one first retransmission process is continued from among the retransmission processes that belong to the new configuration pattern after the reconfiguration, wherein the association relationship is set for each of the plurality of configuration patterns; and selection circuitry, which, in operation, selects data to be retransmitted from among transmission data stored for each retransmission process, based on the first retransmission process and the second retransmission process.

2. The terminal apparatus according to claim 1 , wherein the first frame cycle indicates an interval in the old configuration pattern at which the association relationship between uplink subframe numbers and retransmission process numbers becomes identical and the second frame cycle indicates an interval in the new configuration pattern at which the association relationship between uplink subframe numbers and retransmission process numbers becomes identical.

3. The terminal apparatus according to claim 1 , wherein the determining circuitry, in operation, determines, as the first retransmission process, the retransmission process of the old configuration pattern before the reconfiguration at a first timing at which both subframes are the uplink subframes in the base frame at an identical timing of the configuration patterns before and after the reconfiguration, and determines, as the second retransmission process, the retransmission process of the new configuration pattern at the first timing.

4. The terminal apparatus according to claim 3 , wherein the determining circuitry, in operation, determines, as the first retransmission process, the retransmission process of the old configuration pattern before the reconfiguration at a second timing different from the first timing in the base frame, and determines, as the second retransmission process, the retransmission process of the new configuration pattern after the reconfiguration at a third timing different from the first timing and the second timing.

5. The terminal apparatus according to claim 4 , wherein the determining circuitry, in operation, determines, as the first retransmission process, the retransmission process of the old configuration pattern before the reconfiguration at the earliest timing among a plurality of the second timings.

6. The terminal apparatus according to claim 1 , comprising a receiver, which, in operation, receives information indicating the base frame, wherein the determining circuitry determines the first retransmission process and the second retransmission process based on the base frame indicated in the information.

7. The terminal apparatus according to claim 6 , wherein the information indicates one of a number of frames corresponding to a least common multiple between a frame cycle indicating an interval in the old configuration pattern before the reconfiguration at which the association between the uplink subframe and a retransmission process associated with the uplink subframe becomes identical and the frame cycle in the new configuration pattern after the reconfiguration.

8. The terminal apparatus according to claim 6 , wherein the information indicates a relative positional relationship between the base frame and a frame in which the information is transmitted.

9. A retransmission method for a terminal apparatus capable of reconfiguring a configuration pattern of subframes to one of a plurality of configuration patterns, each of the plurality of configuration patterns defining transmission timings of one or more downlink subframes used for downlink communication and one or more uplink subframes used for uplink communication within a frame, the retransmission method comprising: determining at least one first retransmission process to be continued after reconfiguration of the configuration pattern from among retransmission processes that belong to an old configuration pattern before the reconfiguration, wherein the determination of the at least one first retransmission process is made based on an association relationship between uplink subframe numbers and respective retransmission process numbers within a base frame, the base frame being a frame that includes at least one uplink subframe defined at a same transmission timing as another uplink subframe defined by a new configuration pattern after the reconfiguration, wherein the base frame is assigned a frame number which is divisible by a least common multiple between a first frame cycle associated with the old configuration pattern and a second frame cycle associated with the new configuration pattern, and the association relationship between the uplink subframe numbers and the respective retransmission process numbers within the base frame is uniquely determined by a combination of the old configuration pattern before the reconfiguration and the new configuration pattern after the reconfiguration; determining at least one second retransmission process to which the at least one first retransmission process is continued from among the retransmission processes that belong to the new configuration pattern after the reconfiguration, wherein the association relationship is set for each of the plurality of configuration patterns; and selecting data to be retransmitted from among transmission data stored for each retransmission process, based on the first retransmission process and the second retransmission process.

10. The method according to claim 9 wherein the first frame cycle indicates an interval in the old configuration pattern at which the association relationship between uplink subframe numbers and retransmission process numbers becomes identical and the second frame cycle indicates an interval in the new configuration pattern at which the association relationship between uplink subframe numbers and retransmission process numbers becomes identical.